Mass: The amount of matter present in a body is called its mass. It is an intrinsic property of the body and always remains constant wherever the body is placed. Mass of a body is measured in Kg, gm etc. Mass is measured by using a pan balance.
Weight: Weight is a measurement of how strongly the gravity pulls on a body. We can calculate weight of the body by multiplying its mass by acceleration due to gravity.
According to Newton’s second law
Force (F) = m x a
(where m = mass , a = acceleration)
Like this,
Weight (N) (W) = m X g
(where N= Newton, W= Weight, m = mass in kg, g = acceleration due to gravity)
Weight is measured in Newton. The equation above clears that the weight of the body differs by place. Weight is measured by using spring balance.
Note: The Methods for measuring mass and weight may be interchanged if gravity is known and same, as it is on earth.
Pan Balance
Spring Balance
Example:
Gravity of the place decides the weight of an object.
Eg., there is an object of mass 600 kgs, and gravity on the earth is 10 m/s2 (Actual is 9.8 m/s2). Then its weight would be 6000N, but if we place this object on the moon where gravity is 1/6th of the earth, its weight would be 1000N.
This example proves that mass of an object is always constant, but weight not.
Industrial References: the net weight of packaging of retail items actually refers to mass and is properly expressed in pounds (U.S.) or Kgs. Conversely, the load index rating on automobile tires, which specifies the maximum structural load for a tire in Kgs, refers to weight; that is, the force due to gravity.
Comparison of weights of an object with same mass on different planets and moon:-
| Location | Weight Comparison | Location | Weight Comparison |
|
Weight on Mercury |
0.378 | Weight on Jupiter |
2.36 |
|
Weight on Venus |
0.907 | Weight on Saturn |
0.916 |
|
Weight on Earth |
1.00 | Weight on Uranus | 0.889 |
| Weight on Moon | 0.166 | Weight on Neptune |
1.12 |
| Weight on Mars | 0.377 | Weight on Pluto |
0.071 |
